When electricity is passed through transistors mounted on a printed circuit board (hereinafter "the board"), the transistors, particularly power transistors, generate a substantial amount of heat. The heat must be drawn away from the transistors and dissipated to maintain low temperatures and to avoid damaging the transistors. Conventional transistor heat sinks are mounted on the cases of the transistors sink after electrical leads of the transistors have been inserted and soldered onto the board. However, the transistor case is often drawn against the heat sink when a mounting screw is tightened, so the electric leads have to bend. As a result, stress from bending forces is exerted on the leads and on solder joints that join the leads to the board, wherein the stress can lead to breakage or failure of the transistor.
A second conventional heat sink and transistor assembly includes a heat sink in the form of a cap structure having cooling fins that attach to and fit over one or more transistors. The cap structure is installed after the transistors are soldered to the board, so stress from bending and compression forces is exerted on the leads and solder joints during installation.
Strict manufacturing standards for, as an example, electronic medical devices, require that the case of a transistor have sufficient clearance over the surface of the board, and be spaced apart from other components. Conventional assemblies have experienced significant difficulties maintaining correct positioning of the transistors when they are attached to the board before being secured to a heat sink.
Regardless of which type of conventional heat sink is used, it is necessary to insert and then solder each transistor individually onto the printed circuit board. It is then necessary to perform the often laborious task of fastening one or more heat sinks to the transistor. As a result, manufacturing processes used during installation of the transistors onto the board are very labor intensive, time-consuming, and have a high risk of improper transistor positioning and excessive lead stress, thereby requiring costly rework of the assemblies.
Accordingly, there is a need for an assembly that permits heat sinks to be mounted on transistors and the transistors to be installed on a printed circuit board in a quick and inexpensive manner and in the proper positioning without stressing the transistor leads.